1. What is IPv6?
Internet Protocol version 6 (IPv6) is a network layer IP standard used by
electronic devices to exchange data across a packet-switched internetwork. It
follows IPv4 as the second version of the Internet Protocol to be formally adopted
for general use.
ip v6
it ia a 128 bit size address
here we can see total 8 ocatates each octate size is 16 bits superated with “:”
it is in hexa decimal formate
these 3 types
1.unicast address
2.multicast address
3.anycast address
loopback address of ip v6 is ::1
What is mean by dns,dhcp.?
1. DNS(Domain Name Service):
—————————It’s mainly used to resolve from host name(FQDN-Fully Qualified Domain
Name) to IP address and IP address to host name.DNS mainly used in Internet.
DNS devide in form of hierarchical.
2. DHCP(Dynamic Host Configuration Protocol):
———————————————
DHCP use for provide IP address dnamically to client machine. If that client
not able to find DHCP server then client machine will go for APIPA(We have
range for APIPA which is 169.254.0.1-169.254.255.254).
what is maen different between hub and switch ?
HUB and SWITCH:
——————
Switch is expencive than hub. If more then one user try to send packet at a
time collision will occure but in switch we can send. Switch is full duplex.
Maximum bandwidth is 100 Mhz and that bandwidth is shared by all of the
PC’s connected to the hub. Data can be sent in both directions simultaneously,
the maximum available bandwidth is 200 Mbps, 100 Mbps each way, and
there are no other PC’s with which the bandwidth must be shared.
Difference between Router and Routing: Router: ———
Router is a device which is used to connect different network. A device or setup that
finds the best route between any two networks, even if there are several networks to
traverse. Like bridges, remote sites can be connected using routers over dedicated or
switched lines to create WANs.
Routing: ———Process of delivering a message across one or more networks via the most appropriate
path.
what is a Firewall:
Firewalls are of two types:
-Hardware Firewall
-Software Firewall.
Firewall in simple manner is bascially the utility to provide the security over
the network. These are the security measures that prevents the network’s in
and out traffic to pass through the specific Security filters so that the unwanted
and unsecure data can be stopped from entering into the network..
further… as a security measure it also depends on the network designer and
implementer that how to use a Firewall mean to say the security measures like
how to present the content filtering and Url filtering which type of firewall
should be used and where to put it..
Firewall are the rules which are used for Passing traffic thats is packets in
network layer and frame is datalink layer on a specific port it can be two type
1.Hardware
2.Software
11 TCP is a transport layer protocol sued for reliable delivery of segmented
packets
IP is network layer protocol used for end to end delivery of two nodes not
reliable.
Firewall are two types
1. Hardware Device
2. Software Firewall
Firewall work as a Filter whichever connect to broadband and router before
home Network and stop all virus coming form Internet
A firewall is simply a program or hardware device that filters the information
coming through the Internet connection into your private network or computer
system. If an incoming packet of information is flagged by the filters, it is not
allowed through.
Firewalls use one or more of three methods to control traffic flowing in and
out of the network:
5. What is VTP?
virtual trunking protocol. set up on switches to manage vlans.
What is the difference between TCP and UDP
TCP is a connection oriented protocol, which means that everytime a packet is
sent say from host A to B, we will get an acknowledgement. Whereas UDP on
the other hand, is a connection less protocol.
Where will it be used : TCP -> Say you have a file transfer and you need to
ensure that the file reaches intact, and time is not a factor, in such a case we
can use TCP.
UDP-> Media Streaming, question is say you are watching a movie…would
you prefer that your movie comes..perfectly….but u need to wait a long time
before you see the next frame ?..or would you prefer the movie to keep
streaming…Yes…The second option is definely better….This is when we
need UDP
TCP (Transmission Control Protocol) is a set of rules (protocol) used along
with the Internet Protocol (IP) to send data in the form of message units
between computers over the Internet. While IP takes care of handling the
actual delivery of the data, TCP takes care of keeping track of the individual
units of data (called packets) that a message is divided into for efficient
routing through the Internet.
7 Application
6 Presentation Upper Layers
5 Session
4 Transport
3 Network
2 Data Link Lower Layers
1 Physical
The application, presentation, and session layers are all application-oriented in
that they are responsible for presenting the application interface to the user.
All three are independent of the layers below them and are totally oblivious to
the means by which data gets to the application. These three layers are called
the upper layers.
The lower four layers deal with the transmission of data, covering the
packaging, routing, verification, and transmission of each data group. The
lower layers don’t worry about the type of data they receive or send to the
application, but deal simply with the task of sending it. They don’t
differentiate between the different applications in any way.
The following sections explain each layer to help you understand the
architecture of the OSI-RM (and later contrast it with the architecture of
TCP/IP).
The Application Layer
The application layer is the end-user interface to the OSI system. It is where
the applications, such as electronic mail, USENET news readers, or database
display modules, reside. The application layer’s task is to display received
information and send the user’s new data to the lower layers.
In distributed applications, such as client/server systems, the application layer
is where the client application resides. It communicates through the lower
layers to the server.
The Presentation Layer
The presentation layer’s task is to isolate the lower layers from the
application’s data format. It converts the data from the application into a
common format, often called the canonical representation. The presentation
layer processes machine-dependent data from the application layer into a
machine-independent format for the lower layers.
The presentation layer is where file formats and even character formats
(ASCII and EBCDIC, for example) are lost. The conversion from the
application data format takes place through a “common network programming
language” (as it is called in the OSI Reference Model documents) that has a
structured format.
The presentation layer does the reverse for incoming data. It is converted from
the common format into application-specific formats, based on the type of
application the machine has instructions for. If the data comes in without
reformatting instructions, the information might not be assembled in the
correct manner for the user’s application.
The Session Layer
The session layer organizes and synchronizes the exchange of data between
application processes. It works with the application layer to provide simple
data sets called synchronization points that let an application know how the
transmission and reception of data are progressing. In simplified terms, the
session layer can be thought of as a timing and flow control layer.
The session layer is involved in coordinating communications between
different applications, letting each know the status of the other. An error in
one application (whether on the same machine or across the country) is
handled by the session layer to let the receiving application know that the error
has occurred. The session layer can resynchronize applications that are
currently connected to each other. This can be necessary when
communications are temporarily interrupted, or when an error has occurred
that results in loss of data.
The Transport Layer
The transport layer, as its name suggests, is designed to provide the
“transparent transfer of data from a source end open system to a destination
end open system,” according to the OSI Reference Model. The transport layer
establishes, maintains, and terminates communications between two machines.
The transport layer is responsible for ensuring that data sent matches the data
received. This verification role is important in ensuring that data is correctly
sent, with a resend if an error was detected. The transport layer manages the
sending of data, determining its order and its priority.
The Network Layer
The network layer provides the physical routing of the data, determining the
path between the machines. The network layer handles all these routing issues,
relieving the higher layers from this issue.
The network layer examines the network topology to determine the best route
to send a message, as well as figuring out relay systems. It is the only network
layer that sends a message from source to target machine, managing other
chunks of data that pass through the system on their way to another machine.
The Data Link Layer
The data link layer, according to the OSI reference paper, “provides for the
control of the physical layer, and detects and possibly corrects errors that can
occur.” In practicality, the data link layer is responsible for correcting
transmission errors induced during transmission (as opposed to errors in the
application data itself, which are handled in the transport layer).
The data link layer is usually concerned with signal interference on the
physical transmission media, whether through copper wire, fiber optic cable,
or microwave. Interference is common, resulting from many sources,
including cosmic rays and stray magnetic interference from other sources.
The Physical Layer
The physical layer is the lowest layer of the OSI model and deals with the
“mechanical, electrical, functional, and procedural means” required for
transmission of data, according to the OSI definition. This is really the wiring
or other transmission form.
When the OSI model was being developed, a lot of concern dealt with the
lower two layers, because they are, in most cases, inseparable. The real world
treats the data link layer and the physical layer as one combined layer, but the
formal OSI definition stipulates different purposes for each. (TCP/IP includes
the data link and physical layers as one layer, recognizing that the division is
more academic than practical.)
What is DHCP.
DHCP is a protocol which is designe for Automatic Give the IP Address to
DHCP client..
DHCP Assine the IP Address for few days Lease & capture the clients MAC
address..
It is Updated version of BootP…
DHCP stands for “Dynamic Host Configuration Protocol
DHCP’s purpose is to enable individual computers on an IP network to extract
their configurations from a server (the ‘DHCP server’) or servers, in
particular, servers that have no exact information about the individual
computers until they request the information. The overall purpose of this is to
reduce the work necessary to administer a large IP network. The most
significant piece of information distributed in this manner is the IP address.
1. Can I connect two computers to internet using same line ?
u can connect two computer using NAT wich use port forwarding method and proxy
server same time on the same line
How does a DHCP work ? When a pc with no Ip address just with an MAC
addrress boots up , what are the steps that Happen till the time a Ip is given to
the pc from a DHCP.
DHCP is used for MAC address to IP mapping its support both static and
dynamic mapping.Static mapping are done just like bootstrap and for dynamic
mapping it have database of MAC and IP when a packet with a MAC comes
ask for ip its check that assigne a dynamic IP fixed that for a specific time and
then return that packet with that IP
ping ia process which use ICMP protocl error message which is encapsulated
in a IP packets its calculate the round trip delay time by sending the packet
sending time and subtract it from arrival time. the error messages are
1.destination unrecheable
2.hardware error.
etc
its also sets maximum hop value and after it becomes 0 the packets discarted
Telnet is a application layer process of connection remote compter and local Area
Network compter by specifing the ip address by a specific port,
TCP is a transport layer protocol sued for reliable delivery of segmented packets
IP is network layer protocol used for end to end delivery of two nodes not reliable.
TCP is a connection oriented protocol that provides reliable transfer of information by
synchronization, error checking and sequencing of information to and from IP layer.
IP layer is transport of TCP. It provides path determination and packet
switching. IP layer uses ARP and RARP protocol to map IP to MAC address
and MAC to IP address respectively, to determine network addresses. It is
connectionless protocol that leaves all error checking functions on upper layer.
12. UDP is a connectionless protocol that do not provide reliable transfer of
information and is fast in nature as compare to TCP. This disadvantage on
other hand is suitable for applications like video and voice.
TCP/IP is a two-way communication between the client and the server and it
is a reliable and there is a confirmation regarding reaching the message to the
destination. It is like a phone call.
UDP is a one-way communication only between the client and the server and
it is not a reliable and there is no confirmation regarding reaching the message
to the destination.
Q. Can I connect two computers to internet using same line.
Ans..
Yes, we can connect two or more system using many types of mathodes..
1. Remote Help Invitations.. if you have high or medium speed internet
connection you can access the system..
2. VPN.. using the Virtual Private Network this is technology which is use to
make virtual network between any remote location. VPN make a tunnel type
connection for fast & secure communication.
3. Using third party software we have many type of VPN softwares.
What is a MAC address?
MAC is a machines Physical address, The internet is addressed based on a
logical addressing approach. Say,when the packet reaches say the bridge
connection a LAN, the question is..how does it identify, which computer it
needs to send the packet to. For this it uses the concept of ARP, Address
Resolution Protocol, which it uses over time to build up a table mapping from
the Logical addresses to the Physical addresses. Each computer is identified
using its MAC/Physical address ( u can use the ipconfig -all option to get ur
MAC address).
Ques 2: Diffrence Betw. Switch , Hub, Router..
Hub: 1.it is a layer1 device..used to connect various machine on Lan.
2.It forwards broadcast by default.
3.It supports one collision domain and one broadcast domain.
4.it works on Bus topolog resulting less speed.
Switch: 1. A layer2 device.
2. Forward broadcast first time only.
3. one broadcast domain & colliosion domains depends on no. of ports.
4.It is based on Star Topology giving 100mbps to every pc on Lan.
Router: 1. Does not Broadcast by default.
2. breaks up Broadcast domain.
3. Also called Layer3 switch.
Ques 9: VPN’s
VPN(Virtual Private Network )… these are bascially the logical networks on
the physical line… you can have many VPN oveer same line..
Need of VPN arises when your company need to increase the network but
don’t want to buy any more switches.. take an eg. your dept. your room is
packed with employees and ur company need to add 4 more persons to ur
deptt. what will they do.. the solution is to create VPN’s…you can configure
the switch ports in other deptts. and create a specific VLAN of ur deptt.so that
the persons can sit there and access to the required pcs.
What is ARP/RARP?
ARP: Stands for Address Resolution Protocol…whenever a request is sent by
a node on one network to the node on another network the Physical
address(MAC) is required and for this the IP address need to be flow over the
network..whenver a router with that network (IP) gets the msg. the required
MAC address is sent through the network this process of converting the IP
address to MAC address is Called ARP..and the reverse thats the convertion of
the Mac address to the IP address is called RARP ( Reverse Address
Resolution Protocol)
RARP:RARP is a TCP/ IP protocol term similar to ARP. RARP is the method that
some machines use to determine their own IP address. Essentially, a machine
sends out a packet that includes a machine hardware address. A server on the
same network receives the packet and looks up the hardware address. The
server then sends back the associated IP address of that machine. It is used for
machines that do not have the capability to store their own IP addresses
locally.
ARP:Address Resolution Protocol. ARP is the protocol used by IP (as in TCP/IP)
for address resolution. Address resolution refers to the ability of a station to
resolve another station’s MAC (hardware) address given its IP address.
VLANs logically segment switched networks based on the functions, project
teams, or applications of the organization regardless of the physical location or
connections to the network.
VLANs provide segmentation based on broadcast domains.
All workstations and servers used by a particular workgroup share the same
VLAN, regardless of the physical connection or location.
VLANs are created to provide segmentation services traditionally provided by
physical routers in LAN configurations.
VLANs address scalability, security, and network management. Routers in
VLAN topologies provide broadcast filtering, security, and traffic flow
management.
What is a VPN?
A VPN stands for Virtual Private Network. In english it is a direct tunnel into
a remote network. It allows users to work with certain applications, printers,
network drives and shares as if they where sitting in the office.
How do you distinguish a DNS problem from a network problem?
The first thing to do is to ping any switches, routers, or any other devices on
the network. If your pings come back complete with 0% lost, then it will most
likely be a DNS issue. If you can ping other devices but can not ping the
switch that sits in front of the DNS, then it will be a network issue.
What is a metric?
Routing tables contain information used by switching software to select the
best route.
Routing algorithms have used many different metrics to determine the best
route. Sophisticated routing algorithms can base route selection on multiple
metrics, combining them in a single (hybrid) metric. All the following metrics
have been used:
•Path length
•Reliability
•Delay
•Bandwidth
•Load
•Communication cost
What is the difference between a hub, switch, and router?
Hub works on layer 1 of OSI model
Swich works on layer 2 of OSI model
Router works on layer 3 of OSI model
Hub does not seperate collision and broadcost domain
swich seperate collision domain but does not seperate broadcost domain.
router does seperate collision and broadcost domain
what is socket?
The purpose of the VRRP packet is to communicate to all VRRP routers the
priority and the state of the Master router associated with the Virtual Router
ID.
When a computer program needs to connect to a local or wide area network
such as the Internet, it uses a software component called a socket. The socket
opens the network connection for the program, allowing data to be read and
written over the network. It is important to note that these sockets are
software, not hardware, like a wall socket. So, yes, you have a much greater
chance of being shocked by a wall socket than by a networking socket.
Sockets are a key part of Unix and Windows-based operating systems. They
make it easy for software developers to create network-enabled programs.
Instead of constructing network connections from scratch for each program
they write, developers can just include sockets in their programs. The sockets
allow the programs to use the operating system’s built-in commands to handle
networking functions. Because they are used for a number of different network
protocols (i.e. HTTP, FTP, telnet, and e-mail), many sockets can be open at
one time.
When I ping an IP address the result comes out succesfull, but when I ping
with host name no result comes, ping fails. why?
Because the denied permission had been assigned to ping command (HOST
NAME). Check the Firewall( windows and firewall software)
how to configure DNS in windows O/S with the command or stepes….?
Netsh commands for Interface IP. You can use commands in the Netsh
Interface IP context to configure the TCP/IP protocol (including addresses,
default gateways, DNS servers, and WINS servers) and to display
configuration and statistical information.
USE HELP COMMAND FOR MORE INFORMATION (netsh/?)
What is a full-class C in CIDR notation?
Ans :
For class A ..default subnet mask is 255.0.0.0 so CIDR notation is /8
For class B ..default subnet mask is 255.255.0.0 so CIDR notation is /16
What is a full-class C in CIDR notation
CIDR specifies an IP address range using a combination of an IP address and
its associated network mask. CIDR notation uses the following format xxx.xxx.xxx.xxx/n
Full Class C in CIDR notation can be represented by
Example 10.16.0.0/16
This is a 256 class C = FIRST CLASS B
Now they here are a few more
10.16.0.0/17 is a 128 class C
10.16.0.0/16 is a 64 class C and so on.For class C ..default subnet mask is
255.255.255.0 so CIDR notation is /24
What the Purpose of VLAN?
VLANs can enhance network security.
VLANs increase the number of broadcast domains while decreasing their size.
Network adds, moves, and changes are achieved by configuring a port into the
appropriate VLAN.
A group of users needing high security can be put into a VLAN so that no
users outside of the VLAN can communicate with them.
As a logical grouping of users by function, VLANs can be considered
independent from their physical or geographic locations.
What is OSPF?
Open Shortest Path First
OSPF) is a non-proprietary link-state routing protocol limited to use with the
TCP/IP stack. Open Shortest Path First (OSPF) is an open standards routing
protocol that’s been implemented by a wide variety of network vendors,
including Cisco. If you have multiple routers and not all of them are Cisco, So
your remaining options are basically RIPv1, RIPv2, or OSPF. If it’s a large
network, then, really, your only options are OSPF
OSPF provides the following features:
Consists of areas and autonomous systems
Minimizes routing update traffic
Allows scalability
Supports VLSM/CIDR
Has unlimited hop count
Allows multi-vendor deployment (open standard)
Characteristic of OSPF
Type of protocol - Link-state
Classless support - Yes
VLSM support - Yes
Auto summarization - No
Manual summarization - Yes
Discontiguous support - Yes
Route propagation - Multicast on change
Path metric - Bandwidth
Hop count limit - None
Convergence - Fast
Peer authentication - Yes
Hierarchical network - Yes (using areas)
Updates Event - Triggered
What is Spanning Tree protocol?
In a Layer 2 environment (switching or bridging), however, no routing
protocols are used, and active redundant paths are neither allowed nor
desirable. Instead, some form of bridging provides data transport between
networks or switch ports. The Spanning Tree Protocol (STP) provides network
link redundancy so that a Layer 2 switched network can recover from failures
without intervention in a timely manner. It vigilantly monitors the network to
find all links, making sure that no loops occur by shutting down any redundant
links. STP uses the spanning-tree algorithm (STA) to first create a topology
database, then search out and destroy redundant links.
OSPF
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Describe OSPF in your own words.
OSPF areas, the purpose of having each of them
Types of OSPF LSA, the purpose of each LSA type
What exact LSA type you can see in different areas
How OSPF establishes neighboor relation, what the stages are
If OSPF router is stucked in each stage what the problem is and how to
troubleshoot it
OSPF hierarchy in the single or multi areas. Cool OSPF behavior in broadcast
and nonbroadcast
Draw the diagram of typical OSPF network and explain generally how it
works, DR, BDR, election, ASBR, ABR, route redistribution and
summarization
STP
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How it works and the purpose
Diff types (SSTP, MSTP, RSTP) Cisco - PVST/PVST+
root election
Diff. port stages and timing for convergence
Draw the typical diagram and explain how diff types of STP work
What ports are blocking or forwarding
How it works if there are topology changes
ACLs
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What are they
Diff types
Write an example if you want to allow and to deny…
Well-known port numbers (DNS - 53 and etc…)
QOS
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What is that
What is the diff b/w L2 and L3 QoS
How it works
Network:
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Draw the typical network diagram you have to deal with
explain how it works
What part of it you are responsible
firewall, what is that, how it works, how it is diff from ACLs
What problems with the network you had had and how you solved it.
What are the ways to troubleshoot the network, techniques, commands
network security, ways to achieve it
Switching:
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VLANs
STP
How a L2 switch works with broadcast, unicast, multicast, known/unknown
traffic
VRRP, GLBP
port monitoring and mirroring
L3 switch, how it works
PIM sparse and dense modes
1. Describe the OSI model.
2. What is the difference between a repeater, bridge, router? Relate this to the
OSI model.
3. Describe an Ethernet switch and where it fits into the OSI model.
4. What is a VLAN? What is an ELAN? What is the difference?
5. Relate FDDI/ATM/SONET to the OSI model.
6. Explain how to configure a host network interface (e.g. IP address, netmask,
broadcast address)?
7. Describe Ethernet packet contents: min/max size, header.
8. Describe TCP/IP and its protocols.
9. Describe ATM and what are its current advantages and disadvantages.
10. Describe SONET.
11. What are the maximum distances for CAT5 cabling?
12. Describe UDP and TCP and the differences between the two.
13. What is your current IP address? Hoiw do you find that out on different OSs?
14. Describe what a broadcast storm is.
15. Describe what a runt, a giant, and a late collision are and what causes each of
them.
16. How do you distinguish a DNS problem from a network problem?
17. Describe the Bandwidth Delay problem.
1. Describe the principle of multi-layer switching.
Open Systems Interconnection (OSI) model is a reference model developed by
ISO (International Organization for Standardization) in 1984, as a conceptual
framework of standards for communication in the network across different
equipment and applications by different vendors. It is now considered the
primary architectural model for inter-computing and internetworking
communications.
Communication process has been divided into 7 layers.
1.physical
2.Datalink
3.network
4.transport
5.session
6.presentation
7.application
In all the above layers differnt works are performed according to the work
divided among these layers.
#9 ATM is the short form for Asynchonous Transfer Mode.
Currently ATM is used in places where we require high speed data transfer.
The ATM is a technology of sending and recieving the packets and so it
requires carriers such as SONET/SDH etc. The packet size of the ATM packet
is fixed and is 53 bytes.
Advantages
**********
1. As the packet size is fixed switching can be implemented in Hardware and
so it is very fast.
2. The packet size small and constant so the latency is too small so that it can
support real time data transfer.
3. The ATM supports Quality of Service (QOS).
Disadvantages.
*************
1. The packet size is too small and if u take the additional header that is
attached then it will be huge. So the header size to the actual data send is less
and so overhead is too much.
2. End to end is not ATM and so we still require ATM adapters and other
equipments.
Regards
Ganesh Vasudevan
#2
Repeaters, bridges, and routers are devices used to link individual LANs
together to form larger internetworks. each one operates within a specific layer
of the OSI model.
Repeaters operate at the Physical Layer of the OSI model. They simply listen
to all network traffic on one port and send it back out through one or more
ports, extending smaller networks into a larger, single network. A repeater
simply receives frames, regenerates them, and passes them along. It performs
no processing of the frames or the data they contain.
Relation to OSI Layer Functions
Because repeaters operate at the Physical Layer, they do not need any
addressing data from the frame. Repeaters do not even look at the frames they
are forwarding, passing along even damaged frames. This can be especially
problematic if one segment malfunctions and begins a broadcast storm. All
those erroneous broadcasts are forwarded faithfully by the repeater!
Bridges operate at the Data Link Layer. They use the Data Link Layer and its
physical addressing to join several networks into a single network efficiently.
Bridges join two or more network segments together, forming a larger
individual network. They function similarly to a repeater, except a bridge
looks to see whether data it receives is destined for the same segment or
another connected segment. If the data is destined for a computer on the same
segment, the bridge does not pass it along. If that data is going to a computer
on another segment, the bridge sends it along.
Bridges use a routing table to determine whether data is destined for the local
network or not. On a bridge, the routing table contains MAC addresses. Each
time the bridge receives data, it looks in its routing table to see whether or not
the data is destined for a node on the local network. If it belongs to the local
network, it does not forward the data. If it is not destined for the local network,
it looks in the routing table to determine which physical network the
destination address resides on, and sends the data out onto that network.
Bridges can not join dissimilar networks. If you have an Ethernet network and
a Token Ring network, you cannot use a bridge; you must use a router.
However, a bridge can join networks that use the same frame type but
different media, just like a repeater.
Relation to OSI Layer Functions
Bridges work with the MAC sublayer of the Data Link Layer. Remember that
the Data Link Layer is concerned with communicating on the local network
only. Bridges use information from the MAC sublayer to make decisions on
whether a packet is destined for the same network or another network. The
MAC address is used by bridges to determine first if the destination is local or
not, then to choose which connected network it must go to.
Router:
The Network Layer is concerned with network addressing for larger networks
that consist of many physical networks, often with multiple paths between
them. Routers operate at the Network Layer. They use the addressing
information provided at the network level to join the many networks together
to form an internetwork.
Functions
Routers divide larger networks into logically designed networks. Routers may
seem a lot like bridges, but they are much smarter. Bridges cannot evaluate
possible paths to the destination to determine the best route. This can result in
inefficient use of network resources. Bridges also cannot use redundant paths.
While two bridges can connect two networks, they risk sending packets in an
endless loop between the two networks. This behavior eventually saturates the
network, rendering it unusable.
The drawback to a router’s inherent intelligence is their speed. Because they
process so much information, routers tend to be slower than bridges.
Relation to OSI Layer Functions
Routers operate at the Network Layer of the OSI model. The Network Layer
provides addressing for internetworks, and routers use this addressing
information to determine how to pass along packets of data. Because routers
operate at the Network Layer, they can link different physical network
topologies.
Qustions on Tecnologies like SDH,DWDM,CDMA,PCM & equipments based
on these technology will be helpfull for telelcom people.
#12
Difference between UDP and TCP.
UDP is much faster, used for streaming video and audio files on the net. TCP
is slower, because it contains the main factor UDP does not have, which is
flow/error control.
TCP is used by most users on the net because data transferred needs to be
verified. Error correction allows data to be effectively received
Vlan is virtual lan it used to put some interface in one broadcast domain and
some interfaces in another,it used for security purpose and group departments,
based on the mac address the vlan is configured in the switch ports
TCP/IP is a set of Protocol, which is use to communicate data(packet)between
to host and destination PCs.
TCP(Transmission control protocol)
IP (Internet Protocol)
Tcp/IP work on OSI Model. and Its port is 80.
Repeater is a network device which is use to regenerate packet(data) out of
100m distance of server.
Bridge: it is also a network device which is use to connect multiple Pc in the
network. it is use in small or LANs Network. It work on Layer 2 or 3(some
times)of OSI Model.it is connect pc through HUB.
Router: Router is electronic machine and network device which is work as
gateway.Router connect multiple Network or wireless network between two
office.it base on Layer 3 of OSI Model.
VLAN — Virtual Local Area Network
ELAN — Emulated Local Area Network
Difference between these two are as follows:An ELAN is a type of VLAN over an ATM network. However, it is defined at
the MAC layer while VLANs may be defined by a MAC layer or by a IP
address, including by protocols.
1
state in which a message that has been broadcast across a network results in
even more responses, and each response results in still more responses in a
snowball effect. A severe broadcast storm can block all other network traffic,
resulting in a network meltdown. Broadcast storms can usually be prevented
by carefully configuring a network to block illegal broadcast messages.
HSRP:
Hot Standby Routing Protocol, a proprietary protocol from Cisco. HSRP is a
routing protocol that provides backup to a router in the event of failure. Using
HSRP, several routers are connected to the same segment of an Ethernet,
FDDI or token-ring network and work together to present the appearance of a
single virtual router on the LAN. The routers share the same IP and MAC
addresses, therefore in the event of failure of one router, the hosts on the LAN
are able to continue forwarding packets to a consistent IP and MAC address.
The process of transferring the routing responsibilities from one device to
another is transparent to the user.
VRRP :
Virtual Router Redundancy Protocol, an election protocol that dynamically
assigns responsibility for one or more virtual router(s) to the VRRP router(s)
on a LAN, allowing several routers on a multiaccess link to utilize the same
virtual IP address. A VRRP router is configured to run the VRRP protocol in
conjunction with one or more other routers attached to a LAN. In a VRRP
setup, one router is elected as the master router with the other routers acting as
backups in case of the failure of the master router.
Multilayer switching
Multilayer switching is simply the combination of traditional Layer 2
switching with Layer 3 routing in a single product. Multilayer switching is
new, and there is no industry standard yet on nomenclature. Vendors, analysts,
and editors don’t agree about the specific meaning of terms such as multilayer
switch, Layer 2 router, Layer 3 switch, IP switch, routing switch, switching
router, and wirespeed router. The term multilayer switch seems to be the best
and most widely used description of this class of product that performs both
Layer 3 routing and Layer 2 switching functions.
Multilayer switching is usually implemented through a fast hardware such as a
higher-density ASICs (Application-Specific Integrated Circuits), which allow
real-time switching and forwarding with wirespeed performance, and at lower
cost than traditional software-based routers built around general-purpose
CPUs.
The following are some basic architecture approaches for the multiplayer
switches:
Generic Cut-Through Routing: In the multi-layer switching architecture Layer
3 routing calculations are done on the first packet in a data flow. Following
packets belonging to the same flow are switched at Layer 2 along the same
route. In other words, route calculation and frame forwarding are handled very
differently here.
ATM-Based Cut-Through Routing - This is a variation of generic cut-through
routing which is based on ATM cells rather than frames. ATM-based cutthrough routing offers several advantages such as improved support of LAN
emulation and multi-vendor support in the form of the Multiprotocol Over
ATM (MPOA) standard. Products referred to as IP switches and tag switches
generally fall into this category.
Layer 3 Learning Bridging CIn this architecture, routing is not provided.
Instead, it uses IP “snooping” techniques to learn the MAC/IP address
relationships of endstations from true routers that must exist elsewhere in the
network. Then it redirects traffic away from the routers and switches it based
on its Layer 2 addresses.
Wirespeed Routing - Wirespeed architecture routes every packet individually.
It is often referred to as packet-by-packet Layer 3 switching. Using advanced
ASICs to perform Layer 3 routing in hardware, it implements dynamic routing
protocols such as OSPF and RIP. In addition to basic IP routing, it supports IP
multicast routing, VLAN segregation, and multiple priority levels to assist in
quality of service.
Q#12 - TCP is a connection oriented protocol which works on ACK based
communication. It provides error recovery & detection under Layer 4 of OSI
model. Also, the TCP works in reliable network which offers secured
communication and no loss of data.
UDP is a User Datagram Protocol, used in a faster network. No ACK is
required for the data sent to the network. Also, the application like TFTP
prefers using UDP for its transport layer communication. Its a connectionless
protocol.
CCNA/Cisco admin interview questions
1. You need to retrieve a file from the file server for your word processing
application, which layer of the OSI model is responsible for this function?
1. Presentation layer
2. Application layer
3. Session layer
4. Transport layer
5. Datalink layer
2. You are working in a word processing program, which is run from the
file server. Your data comes back to you in an unintelligible manner.
Which layer of the OSI model would you investigate?
1. Application layer
2. Presentation layer
3. Session layer
4. Network layer
5. Datalink layer
3. The IEEE subdivided the datalink layer to provide for environments that
need connectionless or connection-oriented services. What are the two
layers called?
1. Physical
2. MAC
3. LLC
4. Session
5. IP
4. You are working with graphic translations. Which layer of the OSI model
is responsible for code formatting and conversion and graphic standards.
1. Network layer
2. Session layer
3. Transport layer
4. Presentation layer
5. Which is the best definition of encapsulation?
1. Each layer of the OSI model uses encryption to put the PDU from the
upper layer into its data field. It adds header and trailer information
that is available to its counterpart on the system that will receive it.
2. Data always needs to be tunneled to its destination so encapsulation
must be used.
3. Each layer of the OSI model uses compression to put the PDU from
the upper layer into its data field. It adds header and trailer information
that is available to its counterpart on the system that will receive it.
4. Each layer of the OSI model uses encapsulation to put the PDU from
the upper layer into its data field. It adds header and trailer information
that is available to its counterpart on the system that will receive it.
6. Routers can be configured using several sources. Select which of the
following sources can be used.
1. Console Port
2. Virtual Terminals
3. TFTP Server
4. Floppy disk
5. Removable media
7. Which memory component on a Cisco router contains the dynamic
system configuration?
1. ROM
2. NVRAM
3. Flash
4. RAM/DRAM
8. Which combination of keys will allow you to view the previous commands
that you typed at the router?
1. ESC-P
2. Ctrl-P
3. Shift-P
4. Alt-P
9. Which commands will display the active configuration parameters?
1. show running-config
2. write term
3. show version
4. display term
10. You are configuring a router, which prompt tells you that you are in the
privileged EXEC mode?
1. @
2. >
3. !
4. :
5. #
11. What does the command “IP name-server 255.255.255.255″ accomplish?
1. It disables domain name lookup.
2. It sets the domain name lookup to be a local broadcast.
3. This is an illegal command.
4. The command is now defunct and has been replaced by “IP servername ip any”
12. The following selections show the command prompt and the configuration
of the IP network mask. Which two are correct?
1. Router(config-if)#netmask-format { bitcount | decimal | hexadecimal }
2. Router#term IP netmask-format { bitcount | decimal | hexadecimal }
3. Router(config-if)#IP netmask-format { bitcount | decimal |
hexadecimal }
4. Router#ip netmask-format { bitcount | decimal | hexadecimal }
13. Which layer is responsible for flow control with sliding windows and
reliability with sequence numbers and acknowledgments?
1. Transport
2. Application
3. Internet
4. Network Interface
14. Which processes does TCP, but not UDP, use?
1. Windowing
2. Acknowledgements
3. Source Port
4. Destination Port
15. Select which protocols use distance vector routing?
1. OSPF
2. RIP
3. IGRP
4. PPP
Categories: Networking
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8 Responses to “CCNA/Cisco admin interview questions”
1. Cisco maple Said:
May 23rd, 2005 12:13 am
1. 2
2. 1
3. 3,4
4. 4
5. 2
6. 1,2,3
7. 4
8. 2
9. 1
10. 5
11. 4
12. 3
13. 1
14. 1
15. 2,3
2. right answ Said:
September 4th, 2005 3:35 am
3: 2,3
4: 4
5: 4
6: 1,2
7: 4
8: 2
9: 1
10: 5
13: 1
14: 1,2
15: 2,3
3. just guessing Said:
June 20th, 2007 5:36 am
1). 2
2). 3
3). 2&3
4). 4
5). 4
6). 1&2
7). 2
8). 3
9). 1&3
10). 5
11). 2
12). 1&3
13). 1
14). 1&2
15). 2
4. vianayak Said:
July 16th, 2007 1:31 am
You need to retrieve a file from the file server for your word processing
application, which layer of the OSI model is responsible for this function?
Presentation layer
Application layer
Session layer
Transport layer
Datalink layer
You are working in a word processing program, which is run from the file
server. Your data comes back to you in an unintelligible manner. Which layer
of the OSI model would you investigate?
Application layer
Presentation layer
Session layer
Network layer
Datalink layer
The IEEE subdivided the datalink layer to provide for environments that need
connectionless or connection-oriented services. What are the two layers
called?
Physical
MAC
LLC
Session
IP
5. Nageswara Rao Said:
August 17th, 2007 2:37 pm
1.2
2.2
3.2,3
4.4
5.4
6.1,2
7.2
8.2
9.1
10.5
11.4
12
13.1
14.2
15.2,3
6. Hariom Jindal Said:
September 11th, 2007 4:28 am
Que.15Select which protocols use distance vector routing?
OSPF
RIP
IGRP
PPP
7. Hariom Jindal Said:
September 11th, 2007 4:29 am
Que.15 Select which protocols use distance vector routing?
1. OSPF
2. RIP
3. IGRP
4. PPP
Ans.:
RIP and IGRP use for distance vector routing..
8. ranit Said:
November 19th, 2007 8:05 am
1-3;1-5 ; 3-2,3 ; 4-4 ;5–4; 6–1,2 ; 7–2; 8–2 ; 9–1 ; 0–5 ; 1–2 ; 2–2 ; 3–1 ; 4–1,2
; 5–2,3
Networking and protocols interview questions
Q: What are the seven layers of the OSI model?
A: The layers are physical, data link, network, transport, session, presentation, and
application layers.
Q: In the TCP client-servel model, how does the three-way handshake work in
opening connection?
A: The client first sends a packet with sequence "x" to the server. When the server
receives this packet, the server will send back another packet with sequence "y",
acknowledging the request of the client. When the client receives the
acknowledgement from the server, the client will then send an acknowledge back to
the server for acknowledging that sequence "y" has been received.
Q: What is the purpose of exchanging beginning sequence numbers during the
the connection in the TCP client-server model?
A: To ensure that any data lost during data transfer can be retransmitted.
Q: How does Asynchronous Transfer Mode (ATM) work?
A: ATM works by transmitting all traffic in small, fixed-sized cells. These small,
fixed-size cells reduces queuing delay and can be switched quickly. ATM fits into
layer 2 of the OSI model and provides functions for framing and error correction. At
the port interface, ATM switches convert cells into frames, and vice versa. ATM
provides Quality of Service and traffic shaping.
Q: Given a Class B Network with subnet mask of 255.255.248.0 and a packet
addressed to 130.40.32.16, what is the subnet address?
A: Take the 2 addresses, write them in binary form, then AND them. The answer is
130.40.32.0
Categories: Networking
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5 Responses to “Networking and protocols interview questions”
1. Sreedhar Said:
March 18th, 2005 6:42 am
How duplicated packets are generated in the network?
Answer: Due to re-transmissions
2. Harsha Said:
April 7th, 2005 6:40 pm
This is regarding the question :Q: Given a Class B Network with subnet mask of 255.255.248.0 and a packet
addressed to 130.40.32.16, what is the subnet address?
As the solution mentions, we need to AND the mask and IP. The first two
octets we know represent the network address of the class B IP. From the
given mask, in the third octet, there are five bits for the sub-network, meaning
the subnetwork of the given IP has the value 16. So the sub-network would be
130.40.16.x .
The mentioned answer 130.40.32.0 would be true if the third octet in the mask
was 255.
Comments welcome.
3. tanktop Said:
August 2nd, 2006 3:07 pm
Regarding 2… the answer 130.40.32.0 is correct for the host 130.40.32.16….
130.40.32.0(network) -> 130.40.39.255(broadcast)
4. santhosh Said:
March 2nd, 2007 9:41 am
1.physical layer
2.datalink layer
3.network layer
4.transport layer
5.session layer
6.presention layer
7.application layer
5. Ajay Said:
August 24th, 2007 6:38 am
the address range is correct in that Subnetting Question .
count in the blocks of 16.
130.40.16.0 - 130.40.31.255
130.40.32.0 - 130.40.47.255
130.40.48.0 - 130.40.63.255
and so on…
Question 3: Name the seven layers of the OSI Model and describe them briefly.
Physical Layer - covers the physical interface between devices and the rules by which
bits are passed from one to another.
Data Link Layer - attempts o make the physical link reliable and provides the means
to activate, maintain, and deactivate the link.
Network Layer - provides for the transfer of information between end systems across
some sort communications network.
Transport Layer - provides a mechanism for the exchange of data between end
system.
Session Layer - provides the mechanism for controlling the dialogue between
applications
in end systems.
Presentation Layer - defines the format of the data to be exchanged between
applications
and offers application programs a set of data transformation services.
Application Layer - provides a means for application programs to access the OSI
environment.
Question 4: What is the difference between TCP and UDP?
TCP and UDP are both transport-level protocols. TCP is designed to provide reliable
communication across a variety of reliable and unreliable networks and internets.
UDP provides a connectionless service for application-level procedures. Thus, UDP is
basically
an unreliable service; delivery and duplicate protection are not guareented.
Question 5: What does a socket consists of?
The combination of an IP address and a port number is called a socket.
Networking and Unix interview questions
What is UTP?
UTP — Unshielded twisted pair 10BASE-T is the preferred Ethernet medium of the
90s. It is based on a star topology and provides a number of advantages over coaxial
media:
It uses inexpensive, readily available copper phone wire. UTP wire is much easier to
install and debug than coax. UTP uses RG-45 connectors, which are cheap and
reliable.
What is a router? What is a gateway?
Routers are machines that direct a packet through the maze of networks that stand
between its source and destination. Normally a router is used for internal networks
while a gateway acts a door for the packet to reach the ‘outside’ of the internal
network